Flexible cable harness and image forming apparatus

ABSTRACT

Flexible cables are connected to a movable member at a first end and a fixed member at a second end, each having a curve in between the first end and the second end. The flexible cables each include a first positioning system near the first end in the curve and a second positioning system near the second end in the curve, and they have different distances between the first positioning system and the second positioning system. The first positioning system and the second positioning system are fixed to a first positioning portion and a second positioning portion respectively. The flexible cables are spaced from each other to define clearances thereamong at the curve.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a flexible cable harness for use in an imageforming apparatus. In particular, the invention relates to a flexiblecable harness with a plurality of flexible cables that transmitelectrical signals from a main body to a carriage in an image formingapparatus, such as a printer, a facsimile machine, and a copier.

2. Description of Related Art

Conventionally, there exists ink jet image forming apparatuses, such asa printer, a facsimile machine, and a copier, in which a carriagemounted in an ink cartridge thereon reciprocates in a main scanningdirection to perform printing on a recording medium. In such anapparatus as shown in FIG. 6, a round guide shaft 211 is disposedbetween a left side plate 212 e and a right side plate 212 f, and acarriage 210 is slidingly guided onto the guide shaft 211 to reciprocatein an X direction. The carriage 210 includes a recording head 215 thatejects ink. When the recording head 215 is designed for color printing,it communicates with a control part 200 fixed to a main body of theimage forming apparatus to transmit drive signals via four flexible flatcables (hereinafter referred to as flexible cables) FFC1-FFC4.

The flexible cables FFC1-FFC4 are connected to corresponding connectors201 of the control part 200 at one end and corresponding connectors 203of the recording head 215 at the other end. The flexible cablesFFC1-FFC4 drawn from the connectors 201 are tied in a bundle to a rearframe 212 near the connectors 201 by a binding plate 202 so as toprevent entanglement. The flexible cables FFC1-FFC4 are bent at a curveA and tied in a bundle near the connectors 203 by a binding plate 204.

When the carriage 210 reciprocates in the X direction, the flexiblecables FFC1-FFC4 also move while bending more at the curve A.Especially, the flexible cables located more inward at the curve A maysuffer more stress. Further, while the adjacent cables rub against eachother, they are also subjected to stress. For these reasons, theflexible cables may be prone to damage or breakage at an early stage.

Japanese Laid-Open Patent Publication No. 4-133780 proposes that, as amethod for fixing a plurality of flexible cables in a bundle, eachflexible cable has the same length between two connectors. Each cable isalso provided with its own positioning hole thereon, so as to fit arounda protrusion provided on the carriage.

However, as the length between the connectors is the same on each cable,arranging the connectors separately restricts the connector positions,greatly affects the arrangement of other element parts, and affects thesize of the apparatus. Further, as the positioning hole is disposed atone place in the direction of the length of each cable, the conventionalproblem in that the length between two points to fix each flexible cableby adjusting the position of each cable is not solved.

SUMMARY OF THE INVENTION

The invention thus provides a flexible cable harness whose cables, whichhave different lengths, are set in place easily and free from unduestress at a curve without having to place a restriction on connectorpositions, and an image forming apparatus using such a flexible cableharness.

According to one exemplary aspect of the invention, a flexible cableharness may include a plurality of flexible cables. Each of the cableshas a first end connected to a first object and a second end connectedto a second object, and at least one of the cables contributes to anelectrical connection between the first object and the second object.Each cable includes a curved portion that curves between the first endand the second end, a first positioning system provided near the firstend in the curved portion, and a second positioning system provided nearthe second end in the curved portion. A distance from the firstpositioning system to the second positioning system is different in eachof the plurality of flexible cables such that the more inward theflexible cables are located at the curved portion, the shorter thedistance is between the first positioning system and the secondpositioning system. The first positioning system of each of theplurality of flexible cables is fixed to a first positioning partprovided on or near the first object. The second positioning system ofeach of the plurality of flexible cables is fixed to a secondpositioning part provided on or near the second object. Each cable isspaced in the curved portion.

Thus, the flexible cable harness is structured wherein the flexiblecables located more inward at the curve have a shorter distance from thefirst positioning system to the second positioning system. Thisstructure can prevent breakage or damage to the cables caused bydeflection at the curve area and sets the cables in place without theneed for measuring the distance between the first positioning system andthe second positioning system that varies according to each cable.

Specifically, the first object is a fixed member such as a frame, andthe second object is a movable member such as a carriage. The flexiblecable harness may be structured where the first positioning system ofeach flexible cable may be fixed to a first positioning part providedfixedly with the fixed member, and the second positioning system of eachflexible cable may be provided on or near the movable member and fixedto a second positioning part, which is movable with the movable member.

In an image forming apparatus including the flexible cable harnessstructured as above, a frame may include left and right side platessupporting a guide shaft that guides the carriage in a movable directionand a rear frame provided between the left and right side plates. Thecarriage may have a substantially box shape and two sides forpositioning the recording head. The first positioning part is disposedat a substantially central portion of the rear frame with respect to aleft to right direction thereof, and the second positioning part isdisposed on one of the two sides of the carriage. The flexible cableharness is kept curved when the carriage reciprocates sideways in theframe, however, the flexible cables are spaced from each other to definea clearance thereamong and free from stress caused by collision againsteach other. Thus, with this structure of the harness, its durabilityincreases and a burden on maintenance of the image forming apparatus isreduced, thereby increasing the useful life of the image formingapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described in detail withreference to the following figures wherein:

FIG. 1 is a right side view of a printer also serving as a facsimilemachine as an example of an image forming apparatus applied to anembodiment of the invention;

FIG. 2A is a top view of a recording part in which flexible cables arearranged;

FIG. 2B is a front view of the FIG. 2B;

FIG. 3 shows a film cable and flexible cables which are provided withpositioning systems;

FIG. 4 is a perspective view seen from a rear of the printer showing afirst positioning part disposed on a rear frame;

FIG. 5 is a left side view of a carriage showing a second positioningpart disposed on the carriage; and

FIG. 6 is a schematic top view showing an image forming apparatus foruse with a conventional flexible cable harness.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the invention will be described in detail withreference to the accompanying drawings. As shown in FIG. 1, a printer 1includes a normal facsimile machine function that does the followingaccording to a key input through an operation panel 6: sets variousoperations; reads a document image(s) by a document reading unit 5;converts document images into transmission data; encodes thetransmission data; transmits or receives facsimile data to or from otherfacsimile machines via a communications line; decodes the received data;and performes recording of the decoded facsimile data to a sheet ofpaper P in the recording unit. The printer 1 further includes a copierfunction that scans in a document by a contact image sensor (CIS) of thedocument reading unit 5 to form a color image on a sheet P by each unitof a recording part, a printer function that receives print datatransmitted from an external device such as a personal computer via aprinter cable or by wireless such as infrared radiation to form a colorimage onto a recording sheet P according to the received data, and ascanner function that uses the document reading unit 5 to send the readimage to the external device.

A main case of the printer 1 is made up of a main lower case 1 a and amain upper case 1 b, which are both made from synthetic resin. The lowercase 1 b accommodates an ink jet recording part 2 and includes abackward-leaning paper feed tray 3 disposed at an upper rear part.Recording sheets P for image formation are supplied from the paper feedtray 3 into the printer 1. The lower case 1 a is covered with the uppercase 1 b. On an upper surface of the main upper case 1 b, a documentloading part 4 is disposed toward the rear and the document reading unit5 is disposed toward the front. The document reading unit 5 is coveredwith an operation panel 6 having an operation key part 6 a and a display6 b. The operation key part 6 a includes function keys and a ten-keynumeric pad. The document loading part 4 is provided, on both sides,with a pair of document guide members 8 that guide both side edges of adocument to be conveyed into the document reading unit 5.

An under surface of the main lower case 1 a is covered with a metalbottom cover plate 7, and a control part 100 is disposed in an internalspace of the main lower case 1 a. The control part 100 includes acontrol circuit board, a power supply circuit board, and a networkcontrol unit (NCU) circuit board that allows transmission and receptionof conversation or facsimile data with the party on the end of thetelephone or facsimile machine by telephone lines (which are not shown).A handset (not shown) for two-way conversation with another telephone isplaced on a cradle outwardly projecting from a side of the main lowercase 1 a. A speaker for issuing alarms and monitoring calls is securedto the right rear side of the main lower case 1 a.

The sheets P stacked on the paper feed tray 3 are separated from the topof the stack one by one by a sheet feed roller 21 and a separatordisposed at a rear portion of the main lower case 1 a. The sheet feedroller 21 and the separator are structured as a known paper feedmechanism. The separated sheet P is fed to a conveying roller 22 suchthat the position of the leading edge of the sheet P is adjusted. Thesheet P is then fed between a recording head 15 (FIG. 2) and a platen25, and pinched between a pair of ejecting rollers 23 and 24 disposedvertically on a downstream side of a sheet conveying direction. Whilethe sheet P is pinched and conveyed between the ejecting rollers 23 and24, ink drops are ejected onto the sheet P in accordance with printingcommands to form an image, and the sheet P where the image is formed isejected to a discharged tray 26.

As shown in FIGS. 1 and 2, a round guide shaft 11 is disposed between aleft side plate 12 e and a right side plate 12 f, and a carriage 10 in arecording part 2 is slidably mounted to the guide shaft 11 at its lowerrear end. The recording head 15 of a cartridge type is detachablymounted in the carriage 10 such that the recording head 15 facesdownward and is pinched between left and right side plates 32 of thecarriage 10. To perform color printing, the recording head 15 has fournozzle portions 15 a for ejecting four ink colors of cyan, yellow,magenta, and black respectively, on its lower surface. Ink cartridges16, each containing a corresponding ink which is to be supplied to therecording head 15, are attached to the recording head 15 so as to bedetachable from the top of the recording head 15. The ink cartridges 16are held downward by presser levers 17, which are rotatable frontwardand disposed on the top end of the carriage 10.

A timing belt (not shown) extending parallel with the guide shaft 11 islooped around a driven pulley (not shown), which is disposed to one sideof the rear frame 12, and a driving pulley (not shown), which is fixedto an output shaft of a driving motor, such as a stepping motor, thatcan rotate both clockwise and counterclockwise. The timing belt placedon the pulleys is connected to the carriage 10, thereby enabling thecarriage 10 to reciprocate parallel with the guide shaft 11.

Printing operations by the carriage 10 will be described with referenceto FIG. 2. A maintenance portion 27 is provided on the right side of theplaten 25 outside the recording area. A nozzle wiping device that wipesink drops adhered to the surface of the nozzle portions 15 a of therecording head 15 and a purge device 28 that recovers the state of theink to be ejected from the recording head 15 are disposed in themaintenance portion 27. The purge device 28 is provided with suctioncaps 28 a. The purge device 28 is constructed such that the nozzleportions 15 a of the recording head 15 are covered with thecorresponding suction caps 28 a, a negative pressure generated by a pumpis applied to the nozzle portions 15 a, poor quality ink remaining inthe recording head 15 is removed by suction, and the state of inkejection is recovered. The purge device 28 in the maintenance portion 27is positioned at the home position (at the right end in FIG. 2), and thepurge device 28 also serves as a capping device that covers all thenozzle portions 15 a of the recording head 15 of the carriage 10 toprevent drying of ink. The suction caps 28 a also serve as protectivecaps. A flushing portion 29 that causes ink to be ejected tentativelyfrom each nozzle portion 15 a of the recording head 15 in order toprevent ink clogging is provided on the left end of the platen 25.

A flexible cable harness 109, which is made by tying flexible cables ina bundle and transmits electrical signals between the recording head 15and a control part 100, will be described. The flexible cable harness109 electrically connects the control part 100, that is usually fixed toa bottom plate or a frame of the printer 1 and sends image signals forrecording and control signals, to the recording head 15 thatreciprocates from side to side with respect to FIG. 2 and ejects inkfrom the nozzle portions 15 a in accordance with the image signals andthe control signals. One end of each of the flexible cables (FFC1 toFFCn in FIG. 3), that make up the flexible cable harness 109, isconnected to a corresponding connector 101 provided in the control part100, and the other end is connected to a corresponding connector 103 ofthe recording head 15.

As described above, the flexible cable harness 109 is connected to afixed part at one end and a movable part at the other end. If theflexible cable harness 109 is not fixedly held at any place, it mayunnecessarily contact or rub against other structural elements in theprinter 1 with the movement of the flexible cable harness 109 attachedto the movable part, and may resultantly become damaged. Therefore, theflexible cables coming from the connectors 101 are fixed to the rearframe 12 via a first positioning part 105. The flexible cables are sentfrom the rear of the rear frame 12 (where the control part 100 isplaced) to the front along a first guide part 105 a of the firstpositioning part 105, bent at the front to form a curve A, inserted intoa second positioning part 106 and fixedly held therein.

In detail, the flexible cables are inserted and guided between a secondguide part 106 a and a third guide part 106 b of the second positioningpart 106, and are held in the second positioning part 106. The flexiblecables are further guided inside the carriage 10 along an internalsurface of a fourth guide part 106 e, and connected to the connectors103 of the recording head 15. Thus, the flexible cable 109 is fixed notonly to the connectors 101 and 103 but also at the first and secondpositioning parts 105 and 106. Accordingly, the flexible cable harness109 is fixed at the first positioning part 105, which is the fixed part,and moved by the second positioning part 106 that is moved with thetravel of the carriage 10. Even when the position and the state of thecurve A are changed, the flexible cable harness 109 can communicateelectrical signals without unnecessarily rubbing against the otherstructural elements.

The more internally placed the flexible cables are relative to the curveA, the length of a cable from the first positioning part 105 to thesecond positioning part 106 should be set shorter. However, to fix theflexible cables, measuring the length from the first positioning part105 to the second positioning part 106 every time each one of theflexible cables is arranged is inefficient and may cause an error.Therefore, in the embodiment, a mechanism that can fix and hold theflexible cables with a single motion without the necessity of measuringthe length for each cable is adopted. The details of the mechanism willbe described as follows.

Appropriate spacing among the adjacent flexible cables at the curve A isdetermined by various factors such as the cable elasticity, the numberof cables, the cable thickness, width, length, the size of the curve,and the shape of the curve. When the flexible cable harness 109 is givenan appropriate elasticity to form an optimum curve or the cables arelikely to rub against the other structural elements of the printer 1, afilm cable FC1 (FIG. 3, described later in detail) that does notcontribute to the electrical connection may be used as an interferenceor protective cable and is arranged along other cables so as to beplaced at the outside, inside, or each side of the curve A. Based on thespacing among the adjacent flexible cables determined by the abovefactors, the distance from the first positioning part 105 to the secondpositioning part 106 required for each cable is calculated in such amanner that the more outward at the curve A the flexible cables arelocated, the distance becomes correspondingly longer. The calculatedlength is assigned to each one of the flexible cables.

The distance between the two positioning places, which varies accordingto each cable, will be described in detail with reference to FIG. 3. InFIG. 3, the film cable FC1 is made of a film that does not contribute toan electrical connection and has a length L between the two positioningplaces. A flexible cable FFC1 is located outside the flexible cable FC1at the curve A and has a length L1 between the two positioning places. Aflexible cable FFC2 is located outside the cable FFC1 at the curve A andhas a length L2 between the two positioning places. A flexible cableFFCn is placed outermost at the curve A and has a length Ln between thetwo positioning places. Flexible cables FFC3 to FFCn-1 are not shown inFIG. 3. As shown in FIG. 2, the flexible cables FFC1 to FFCn areconnected to the control part 100 at their left ends and to therecording head 15 at their right ends, thereby contributing to anelectrical connection between the control part 100 and the recordinghead 15. A beginning of the film cable FC1 is at the first positioningpart 105 and an end of the film cable FC1 is at the second positioningpart 106.

The film cable FC1 is provided with a first positioning system 107 atthe left end (shown in FIG. 3). The first positioning system 107includes a pair of positioning holes 107 c aligned vertically across thewidth of the film cable FC1. Projections 105 c (FIG. 4) of the firstpositioning part 105 are to be inserted into the positioning holes 107c. The film cable FC1 is provided with a second positioning system 108at the right side (shown in FIG. 3) thereof. The second positioningsystem 108 includes a pair of positioning holes 108 c aligned verticallyacross the width of the film cable FC1. Projections 106 c (FIG. 5) ofthe second positioning part 106 are to be inserted into the positioningholes 108 c. The first positioning system 107 and the second positioningsystem 108 are integrally formed with the film cable FC1. In this case,a length between the first positioning system 107 and the secondpositioning system 108, in other words, a length between a center lineof the positioning holes 107 c and a center line of the positioningholes 108 c, is set to the length L.

Similarly, the flexible cables FFC1 to FFCn each have a firstpositioning system 107 with a pair of positioning holes 107 c alignedvertically across their width near their left ends. The projections 105c of the first positioning part 105 are to be inserted into thepositioning holes 107 c. Further, the flexible cables FFC1 to FFCn eachhave a second positioning system 108 with a pair of positioning holes108 c aligned vertically across their width near their right ends. Theprojections 106 c of the second positioning part 106 are to be insertedinto the positioning holes 108 c.

In the embodiment, the first positioning system 107 and the secondpositioning system 108 provided on each of the flexible cables FFC1 toFFC are formed by bonding tab-shaped sheets 107 a and 108 a, which havebeen punched separately, to bonded surfaces 107 b and 108 b at both endsof the cable using adhesive or double-faced tape. Not being limited tothis, however, the first positioning system 107 and the secondpositioning system 108 may be integrally formed with the flexible cableFFC1 to FFCn during manufacturing, as is the case with the film cableFC1.

When the first and second positioning systems 107 and 108 are attachedto each cable FFC1 to FFCn, the manufacturing of various flexible cablesis simplified. When the first and second positioning systems 107 and 108are integrally formed with each cable, it is necessary to provideproduction facilities with a plurality of presses in order to make thefirst and second positioning systems 107 and 108 at different positions.On the other hand, when the first and second positioning systems 107 and108 are attached, new facilities that do not include the machine thatmake the tab-shaped sheets 107 a and 108 a are not necessary.

When the first and second positioning systems 107 and 108 are integrallyformed with each cable FFC1 to FFCn, manufacturing processes can bereduced, production costs can be reduced, and positioning fluctuationscan be minimized.

When the tab-shaped sheets 107 a and 108 a are bonded to a specificplace on each of the flexible cables FFC1 to FFCn, the use of a jig,where the lengths of the flexible cables for bonding are indicatedbeforehand, may facilitate bonding precisely and smoothly without theneed to measure such lengths as occasion demands.

In any of these instances, the length between the first positioningsystem 107 and the second positioning system 108 (the length between thecenter line of the positioning holes 107 c and the center line of thepositioning holes 108 c) is set to any of the lengths L1 to Ln which areallocated to the cables. In the example shown in FIG. 3, the length L isthe shortest, and the length Ln is the longest. In other words, thefollowing equation holds: L<L1<L2< . . . <Ln-1<Ln. A difference of eachlength between L and L1, between L1 and L2, . . . between Ln-1 and Ln isset such that a curvature radius at the curve A is reduced by aspecified amount as the flexible cables FFC1 to FFCn are located moreinward at the curve A. However, it can be changed according to the shapeof the curve A and the material used for the cable.

Specifically, in the embodiment, each of the cables FC1, FFC1 to FFCn ismade of a 0.15 mm-thick and nearly 20 mm-wide flame-retardant polyesterfilm sheet (for cables FFC1 to FFCn, further done with conductorwiring). The difference in length between the adjacent cables, that is,between L and L1, between L1 and L2, . . . between Ln-1 and Ln is set to1.5 mm. However, it is not limited to this value. It should be taken forgranted that an optimum cable length difference may vary according tothe cables thickness and materials to be used. In the case of flexiblecables used in general printers, when the length difference is from 1 mmto 3 mm, problems caused by cable deflection, such as cable breakage orfrequent contacts between the cables can be prevented, and damage orbreakage at an early stage can be also prevented.

The first positioning part 105 where the first positioning system 107for each of the flexible cables FC1 and FFC1 to FFCn is fixedlymaintained will be described in detail with reference to FIG. 4. Thefirst positioning part 105 is inserted into a substantially rectangularopening 12 g provided in a specified position of the rear frame 12 fromthe rear of the rear frame 12 (the side where the control part 100 shownin FIG. 2 is located). The first positioning part 105 has theprojections 105 c, which are vertically aligned with respect to thecable width direction so as to be engaged in the positioning holes 107 cformed in the first positioning system 107 provided on each of theflexible cables FC1 and FFC1 to FFCn. In the embodiment, the film cableFC1 to be positioned inner mostly at the curve A (FIG. 2) is firstplaced in the first positioning part 105, and the flexible cables FFC1to FFCn are overlaid on the film cable FC1 in this order. Finally, a lid105 b is closed in a direction of arrow C, thereby the first positioningsystem 107 of each cable can be reliably fixed to the first positioningpart 105. Ends extending leftward from the first positioning systems 107of the flexible cables FFC1 to FFCn shown in FIG. 3, exclusive of thefilm cable FC1, are connected to the control part 100 (FIG. 2), and theright ends of the flexible cables FFC1 to FFCn inclusive of the filmcable FC1 (shown in FIG. 3) are sent along the first guide part 105 afrom the opening 12 g to the front of the printer 1, curved to form thecurve A, and taken in the carriage 10 (FIG. 2).

In the carriage 10 as shown in FIG. 5, the film cable FC1 and theflexible cables FFC1 to FFCn are attached to the third guide part 106 bof the second positioning part 106, which is formed in a ribbed shape onthe left side plate 32 of the carriage 10. The two positioning holes 108c of the second positioning system 108 provided on each of the filmcable FC1 and the flexible cables FFC1 to FFCn are fitted over the twoprojections 106 c formed on the left side plate 32 of the carriage 10,so that the cables are positioned in place. The second positioning part106 is mounted on the left side plate 32 so as to cover the secondpositioning system 108 of each cable. The flexible cables FFC1 to FFCnare inserted into the second positioning part 106 with a specified angleθ (FIG. 2) relative to a direction perpendicular to the travel directionof the carriage 10 by the guide of the second guide part 106 a and thethird guide part 106 b. The flexible cables FFC1 to FFCn are broughtinside the carriage 10 as shown in FIG. 2, a presser lid 106 d is closedin such a manner as to fold into the direction of arrow D in FIG. 5,thereby the second positioning system 108 of each cable is reliablyfixed on the carriage 10. Thereafter the flexible cables FFC1 to FFCnare connected to the connectors 103 of the recording head 15. Then, therecording head 15 is mounted on the carriage 10.

In the conventional structure shown in FIG. 6 where the binding plates204 allow the flexible cable harness 207 to be sent in parallel with thedirection X of which the carriage 210 moves, the flexible cable harness207 may heavily collide against the left side plate 212 e at the curve Aand may swing from the binding plates 204 greatly and vertically, andreaction stress may focus on the curve A of the flexible cable harness207 or around the binding plates 204, causing breakage of the cables atan early stage. Although it is not shown, for the sake of scattering thereaction stress applied to the curve A and the binding plates 204around, it can be considered that the binding plates 204 may be modifiedto guide the harness in a lower-left direction in FIG. 6. However, whenthe carriage 210 moves toward the left end in FIG. 6, the arc of thecurve A will expand and a great space to the left side plate 212 e or tothe lower-left part of the figure will be needed. If there is no spacefor it, the curve A may be pushed into or collide against the left sideplate 212 e, thereby increasing the stress applied to the curve A andthe binding plates 204 around.

In the embodiment, as shown in FIG. 2, the second guide part 106 a andthe third guide part 106 b of the second positioning part 106 pinch theflexible cable harness 109 from both sides thereof so as to guide itwith a specified angle θ toward the first positioning part 105, relativeto the direction perpendicular to the travel direction of the carriage10. In this case, the angle θ for example is an angle with which eachcable can be bent toward the first positioning part 105 withoutsuffering undue stress even when the carriage 10 moves to the left endor the center in the figure. As the angle θ becomes a part of thecurvature of the curve A, even when the carriage 10 moves to the leftend (a position indicated by a double dashed chain line), each cable isset with such an angle so as to be free from undue stress capable offorming the curve A with the necessary curvature and eliminates the needfor a great space in a main scanning direction. Thus, this prevents thecables from being broken by stress fatigue generated by collidingagainst the left side plate 12 e at the curve A. To obtain the aboveeffect, it is desirable that the angle θ is within the range of 35° to60°. In the embodiment, the second guide part 106 a and the third guidepart 106 b are formed such that the angle θ is 50°. However, the optimumvalue for the angle θ varies depending on the material used for theflexible cables FFC1 to FFCn, their thickness, a positional relationshipbetween the control part 100 and the carriage 10, and the movable rangeof the carriage 10.

In FIGS. 4 and 5, the diameter of the positioning holes 107 c and 108 cprovided on the first and second positioning systems 107 and 108 isshown larger than the diameter of the projections 105 c and 106 cprovided on the first and second positioning parts 105 and 106, howeverit can be decreased. Especially when the positioning holes 107 c and 108c are provided on the resilient tab-shaped sheets 107 a and 108 a orintegrally provided with the film cable FC1 or the flexible cables FFC1to FFCn, decreasing the diameter of the positioning holes 107 c and 108c smaller than the diameter of the projections 105 c and 106 c makes thepositioning holes 107 c and 108 c tightly fit around the projections 105c and 106 c, thereby reliably engaging each other. This prevents thecables from loosening and coming apart when the cables are attached tothe first and second positioning parts 105 and 106 or the structuralelements of the first and second positioning parts 105 and 106 aremounted.

The flexible cables FFC1 to FFCn in the embodiment are set and kept inplace with a two-point attachment, the two positioning holes 107 c and108 c are each provided on both ends thereof. Compared with asingle-point attachment, cables do not rotate around a positioning pointas a pivot and are not inclined and displaced.

As described above, the tab-shaped positioning systems 107 and 108 areintegrally formed with or separately attached to each cable at the twospecified places with respect to its length. However, other shapes ormechanisms can be used without departing from the scope of theinvention. The above embodiment has been described with a case where thecables are connected to the fixed part at one end and the movable partat the other end, however both ends of the cable harness can beconnected to the fixed part or different movable parts as long as theharness is curvedly connected between two points. Further, theembodiment has been described with a flexible cable harness made of aplurality of flexible flat cables, however, it is not limited to this.The invention can be put into practice as long as a harness is made ofsimilar flexible cables.

According to the embodiment, the flexible cable harness 109 is connectedto the fixed part (the control part 100) at one end and the movable part(the carriage 10) at the other end and includes a plurality of flexiblecables FFC1 to FFCn tied in a bundle, and at least one of the cablescontributes to the electrical connection between the fixed part and themovable part. Each of the flexible cables FFC1 to FFCn is bent betweenone end and the other end thereof to form the curve A, and includes thefirst positioning system 107 near one end and the second positioningsystem 108 near the other end. The distance between the firstpositioning system 107 and the second positioning system 108 variesdepending on the flexible cables FFC1 to FFCn. As the first and secondpositioning systems 107 and 108 are attached to the first and secondpositioning parts 105 and 106 respectively, the flexible cables FFC1 toFFCn are spaced from each other at the curve A. Thus, there is no needto set the flexible cables FFC1 to FFCn in place by measuring the lengthbetween the two positioning systems (L, L1, L2, . . . , Ln) that variesaccording to each cable. Upon manufacturing or maintenance of anapparatus using the flexible cable harness 109, the flexible cables FFC1to FFCn can be set in place easily.

Further, the flexible cable harness 109 is structured wherein theflexible cables located more inward at the curve A have a shorterdistance from the first positioning system 107 to the second positioningsystem 108. This structure can prevent breakage or damage to the cablesFFC1 to FFCn caused by deflection at the curve A and sets the cablesFFC1 to FFCn in place without the need for measuring the distancevarying according to each cable.

The flexible cable harness 109 is structured wherein the distancebetween the first positioning system 107 and the second positioningsystem 108 is set in each cable such that a curvature radius at thecurve A is reduced by a specified amount as the flexible cables FFC1 toFFCn are located more inward at the curve A. With this structure, aslong as the distance from the first positioning system 107 to the secondpositioning system 108 is determined for the outermost and innermostcables, it is easy to determine the distance for other cables betweenthe innermost and outermost cables.

In the flexible cable harness 109, the flexible cables FFC1 to FFCn areset in position by engagement with the first and second positioningsystems 107 and 108 and the first and second positioning parts 105 and106. This structure enables a snap attachment of the cables, and isextremely effective even when maintenance is performed where a number ofadjustment tools can not be prepared. Further, the first and secondpositioning systems 107 and 108 are provided on the shorter side (i.e.,inner side) of each of the flexible cables FFC1 to FFCn, and thepositioning holes 107 c and 108 c thereof, which are provided outsideacross the width of each cable, are fitted around the correspondingprojections 105 c and 106 c provided on the first and second positioningparts 105 and 106. Thereby the flexible cables FFC1 to FFCn are set inplace. In other words, with a simple engagement of holes andprojections, the first and second positioning systems 107 and 108 can bereasonably manufactured and the necessary positioning accuracy can bealso ensured.

In the printer 1 using the flexible cable harness 109, the fixed part isthe control part 100, the movable part is the carriage 10 mounting therecording head 15 thereon, the flexible cable harness 109 is connectedbetween the control part 100 and the carriage 10. Thus, it is possibleto provide an image forming apparatus that is compact in size, highlydurable, and facilitates manufacturing and maintenance. The firstpositioning part 105 and the second positioning part 106 include theprojections 105 c and 106 c, and lids 105 b and 106 d that cover and fixthe first positioning system 107 and the second positioning system 108engaged with the projections 105 c and 106 c, respectively. Thus, in theprinter 1, the flexible cables FFC1 to FFCn can be attached with a snap,and it is extremely effective even when maintenance is performed where anumber of adjustment tools can not be prepared.

While the invention has been described in detail with reference to aspecific embodiment thereof, it should be apparent to those skilled inthe art that various changes and modifications may be made thereinwithout departing from the spirit and scope of the invention.

1. A flexible cable harness, comprising: a plurality of flexible cables, each having a first end connected to a first object and a second end connected to a second object, at least one of the plurality of flexible cables contributing to an electrical connection between the first object and the second object, each of the plurality of flexible cables comprising: a curved portion that curves between the first end and the second end; a first positioning system added near the first end in the curved portion; and a second positioning system added near the second end in the curved portion, wherein a distance from the first positioning system to the second positioning system is different in each of the plurality of flexible cables such that more inward flexible cables located at the curved portion are shorter in distance between the first positioning system and the second positioning system, the first positioning system of each of the plurality of flexible cables is fixed to a first positioning part provided on or near the first object, the second positioning system of each of the plurality of flexible cables is fixed to a second positioning part provided on or near the second object, and each of the plurality of flexible cables are spaced in the curved portion.
 2. The flexible cable harness according to claim 1, wherein the first object is a fixed member, the second object is a movable member, the first positioning system of each of the plurality of flexible cables is fixed to the first positioning part provided fixedly with the fixed member, and the second positioning system of each of the plurality of flexible cables is provided on or near the movable member and fixed to the second positioning part movable with the movable member.
 3. The flexible cable harness according to claim 1, wherein the distance from the first positioning system to the second positioning system is set in each of the plurality of flexible cables such that a curvature radius of the curved portion is reduced by a specified amount as the flexible cables are located more inward at the curved portion.
 4. The flexible cable harness according to claim 1, wherein the first positioning system and the second positioning system are integral with each of the plurality of flexible cables.
 5. The flexible cable harness according to claim 1, wherein the first positioning system and the second positioning system are separate pieces and added to each of the plurality of flexible cables.
 6. The flexible cable harness according to claim 1, wherein the flexible cables are set in position by engagement of the first positioning system with the first engagement part and the second positioning system with the second engagement part.
 7. The flexible cable harness according to claim 1, wherein each of the first positioning system and the second positioning system is provided on a shorter side of each of the plurality of flexible cables, and includes a hole provided beyond a width of each of the plurality of flexible cables, the hole is engaged with a corresponding protrusion provided on each of the first positioning part and the second positioning part in order to set the cables in place.
 8. The flexible cable harness according to claim 1, wherein each of the first positioning system and the second positioning system include two holes spaced from each other, and each of the first positioning part and the second positioning part includes two protrusions corresponding to the two holes.
 9. The image forming apparatus according to claim 1, wherein the plurality of flexible cables are tied in a bundle.
 10. An image forming apparatus including the flexible cable harness according to claim 2, wherein the fixed member is a control circuit board fixed to a frame, the movable member is a carriage mounting a recording head thereon, and the flexible cable harness is connected to the control circuit board on the first end and the carriage on the second end.
 11. The image forming apparatus according to claim 10, wherein the frame includes left and right side plates supporting a guide shaft that guides the carriage in a movable direction and a rear frame provided between the left and right side plates, and the carriage has a substantially box shape and two sides for positioning the recording head, the first positioning part is disposed at a substantially central portion of the rear frame with respect to a left to right direction thereof, and the second positioning part is disposed on one of the two sides of the carriage.
 12. The image forming apparatus according to claim 11, wherein the first positioning part and the second positioning part include protrusions engageable with the holes of the first positioning system and the second positioning system and lids that cover and fix the first positioning system and the second positioning system respectively.
 13. The image forming apparatus according to claim 11, wherein the second positioning part is provided with a guide portion that guides the flexible cable harness extending from the first positioning part therein invariably at a specified angle relative to a direction perpendicular to a travel direction of the carriage.
 14. The image forming apparatus according to claim 13, wherein the guide portion includes a pair of guide members to pinch and guide the flexible cable harness from both sides thereof.
 15. The image forming apparatus according to claim 13, wherein the specified angle is from 35° to 60°.
 16. A flexible cable harness, comprising: a plurality of flexible cables, each having a first end connected to a first object and a second end connected to a moveable second object, at least one of the plurality of flexible cables contributing to an electrical connection between the first object and the second object, each of the plurality of flexible cables comprising: a curved portion that curves between the first end and the second end; a first positioning system added near the first end in the curved portion; and a second positioning system added near the second end in the curved portion, wherein the first positioning system of each of the plurality of flexible cables is fixed to a first positioning part provided on or near the first object, the second positioning system of each of the plurality of flexible cables is fixed to a second positioning part provided on or near the second object, and the second positioning part is provided with a guide portion that guides the flexible cable harness extending from the first positioning part therein invariably at a specified angle relative to a direction perpendicular to a travel direction of the second object.
 17. The flexible cable harness according to claim 16, wherein a distance from the first positioning system to the second positioning system is different in each of the plurality of flexible cables such that more inward flexible cables located at the curved portion are shorter in distance between the first positioning system and the second positioning system and each of the plurality of flexible cables are spaced in the curved portion. 